buffindexed: could not open overview

[Russ Allbery]

Alex Kiernan <alexk at demon.net> writes:

> I'm almost certain that all of our concurrent file based locking where
> we're using mmap is broken on SMP (and it'll depend on your architecture
> whether its really broken or just theoretically broken). On SMP the
> locking primitives for concurrent code use memory barrier operations to
> ensure that all CPUs have consistent caches; the lock file stuff we're
> using I suspect doesn't generate the right memory barriers so we manage
> to exit critical regions with inconsistent cache views of the mmap()ed
> regions on different CPUs which means we get all confused about the
> state of the bitmaps.

Hm, that sounds like an operating system bug to me.  Why wouldn't the
operating system make sure that fcntl works properly with SMP?

-- 
Russ Allbery (rra at stanford.edu)             <http://www.eyrie.org/~eagle/>

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